How did the Civil War come about?
Disagreements between Charles I and the parliament had been simmering for several years. Charles had been exercising too much power, such as raising taxes unreasonably and imprisoning without trial those who did not pay up, and had been ignoring the wishes of parliament.
Civil war broke out in 1642. At first, Charles's Royalist forces had the upper hand, with further promise of support from the Irish Catholic Confederation, which was fighting Parliamentarian forces in Ireland.
But in 1643 an agreement between English and Scottish parliaments brought the Scottish army into the war, and the balance changed. At the battles of Naseby and Langport in June and July 1645, the first showing of the Parliamentarian New Model Army under Thomas Fairfax and Oliver Cromwell, the Royalists suffered major losses.
Charles I's surrender in May 1646 concluded the first phase of the civil war, though he rejected all proposals intended to bring a peace. However, he did reach a secret agreement with the Scots regarding Presbyterianism in England, which incensed the English Parliament.
How did Charles's execution come about?
The Civil War reached the end of its next phase with Charles's trial and execution in January 1649. The charges against him were noted in a special Act of Parliament, namely that he “had a wicked design totally to subvert the ancient and fundamental laws and liberties of this nation”, and that he had “levied and maintained a civil war in the land." The latter was the equivalent of treason, though the basis for it was weak.
The decision that the King would have to be executed and the monarchy abolished had come to Cromwell once he realised the gulf between King and Parliament could never be bridged.
There was not much support for it in Parliament, which had to be purged of royalist sympathisers, to leave a core (known as the Rump Parliament) of 80 MPs. The House of Lords refused to acknowledge the process and the House of Commons took the unprecedented vote of excluding the Lords and acting on its own. It was this reduced Rump Parliament that voted through the ordinance agreeing the King's trial. The reduced Parliament was, in effect, a High Court of Justice. The King refused to acknowledge the court or the charges and did not testify on his own behalf.
The trial and its legal basis corrupted the very freedoms and liberties over which the Civil War had been fought. His execution was on a cold and solemn day and the assembled crowd groaned as the axe severed his head.
How did the execution change things?
Charles had borne his final moments with great dignity, claiming he was a “martyr of the people”. The execution not only severed his head from his body, but severed the link with the old-style of feudal and all-powerful monarch. Although the monarchy would be restored eleven years later, and although there had to be another revolution in 1688, to the country the king was no longer unassailable. No matter how illegally it was achieved, Parliament had asserted its own right.
What does this show?
This is Charles's death warrant, signed by 59 individuals. After the Restoration of the Monarchy in 1660, only 38 of those were still alive. Some had fled the country, but of the others 9 were executed and 15 were imprisoned. Only one, Richard Ingoldsby, was pardoned and allowed to keep his lands. He claimed Cromwell had seized his hand and forced him to sign the warrant.
At the high Co[ur]t of Justice for the tryinge and judginge of Charles
Steuart Kinge of England January xxixth Anno D[omi]ni 1648.
Whereas Charles Steuart Kinge of England is and standeth convicted attaynted and condemned of High Treason
and other high Crymes, And sentence uppon Saturday last was pronounced against him by this Co[ur]t to be putt to death by the
severinge of his head from his body Of w[hi]ch sentence execuc[i]on yet remayneth to be done, These are therefore to will and
require you to see the said sentence executed In the open Streete before Whitehall uppon the morrowe being the Thirtieth day of
this instante moneth of January betweene the houres of Tenn in the morninge and Five in the afternoone of the same
day w[i]th full effect And for soe doing this shall be yo[u]r sufficient warrant And these are to require All Officers and Souldiers
and other the good people of this Nation of England to be assistinge unto you in this service Given under o[ur] hands and
To Colonell Francis Hacker, Colonell Huncks
and Lieutenant Colonell Phayre and to every
Har. Waller Hen. Smyth A. Garland Symon Mayne Tho. Wogan
John Blakiston Per. Pelham Edm. Ludlowe Tho. Horton John Venn
M. Livesey J. Hutchinson Ri. Deane Henry Marten J. Jones Gregory Clement
Jo. Bradshawe John Okey Willi. Goffe Robert Tichborne Vinct. Potter John Moore Jo. Downes
Tho. Grey J. Da[n]vers Tho. Pride H. Edwardes Wm. Constable Gilbt. Millington Tho. Wayte
O. Cromwell Jo. Bourchier Pe. Temple Daniel Blagrave Rich. Ingoldesby G. Fleetwood Tho. Scot
Edw. Whalley H. Ireton T. Harrison Owen Rowe Willi. Cawley J. Alured Jo. Carew
Tho. Mauleverer J. Hewson Willm. Purefoy Jo. Barkstead Robt. Lilburne Miles Corbet
Ad. Scrope Isaa. Ewer Will. Say
James Temple John Dixwell Anth. Stapley
Valentine Wauton Greg. Norton